242 THE DEPTHS OF THE SEA. [ CHAP. VI. 
round iron of the same thickness, dividing beneath 
into two branches, which are attached to the ends of 
the cross-bars by eyes allowing the arms to fold down 
over the dredge-mouth, meet in two heavy eyes at a 
point eighteen inches above the centre of the frame. 
The total weight of the dredge-frame and arms is 
twenty pounds. It ought to be of the best Low- 
moor or Swedish wrought-iron. I have seen a stout 
dredge-frame of Lowmoor iron twisted like a bit 
of wax in extricating it from a jam between two 
stones, and, singularly enough, the dredge which 
came up in that condition contained the unique 
example of an echinoderm never found before or 
since. 
The thick inner edges of the scrapers are perforated 
by round holes at distances of about an inch, and 
through these, strong iron rings about an inch in 
diameter are passed, and two or three like rings run 
on the short rods which form the ends of the dredge- 
frame. <A light iron rod bent to the form of the 
dredge opening usually runs through these rings, and 
to this rod and to the rings the mouth of the dredge- 
bag is securely attached by stout cord or strong 
copper wire. 
In the dredge now before me, which has worked 
well and seen good service, the bag is two feet in 
depth, and is of hand-made net of very strong twine, 
the meshes half an inch to the side. So open 
a network would let many of the smaller things 
through, and to avoid this the bottom of the bag, 
to the height of about nine inches, is lined with 
‘bread-bag,’ a light open kind of canvas. 
Many other materials have been used for dredge- 
